B&W images stored in pdf are too big

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Michel-nk
Posts: 2
Joined: Fri Sep 06, 2013 7:47 am

B&W images stored in pdf are too big

Post by Michel-nk »

When i save black and white image in PDF-format, xnview stores them in this manner:

...
/Type /XObject
/Subtype /Image
/Name /Im0
/Filter [ /ASCII85Decode ] :?
/Width XXXX
/Height YYYY
/ColorSpace 11 0 R
/BitsPerComponent 8
/Length 10 0 R
>>
stream
!<<*!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8
W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!
s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W
-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s
8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-!s8W-
...

and pdf's size becomes ... very very very monstrous. :x

But after converting source to grey, pdf becomes normal size.

Dear Author! Please, provide possibility to automatic(implicit) B&W to grey-scale image converting before putting it in PDF. Or fully change storage method for B&W images in PDF.

Thank you!
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xnview
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Re: B&W images stored in pdf are too big

Post by xnview »

In greyscale, it's smaller because you use JPEG compression, right?
Pierre.
Michel-nk
Posts: 2
Joined: Fri Sep 06, 2013 7:47 am

Re: B&W images stored in pdf are too big

Post by Michel-nk »

xnview wrote:In greyscale, it's smaller because you use JPEG compression, right?
Yes, right. But i can't apply this compression method to B&W-images when store them in PDF. How can i do this?
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xnview
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Re: B&W images stored in pdf are too big

Post by xnview »

Yes, the only way is to convert them in greyscale before
Pierre.
cday
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Location: Cheltenham, U.K.

Re: B&W images stored in pdf are too big

Post by cday »

Black and white images saved as TIFFs with Fax compression can be very small -- much smaller than a grayscale JPEG -- and when a PDF file is created from a TIFF image, Fax is one of the compression option available.

I think you could be quite surprised at the small file sizes that result when a black and white image is saved as a TIFF, or a TIFF image saved as a PDF, when Fax compression is selected. Fax is also lossless compression, unlike JPEG, so even when the file size is very small there is no loss of quality.
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